grep.tcz vs busybox grep speed

[jazzbiker]

Since this appears to be a fairly simple search, I decided to run
some benchmarks.

Hi Rich, just for more detailed picture may I ask You to provide the tests You've already run with the pattern closer to Leee's one? Upon the same environment using wildcards and anchors, something like

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tc@E310:~/onboot$ export X="usr\/local\/bin\/zvbi-atsc-c."
tc@E310:~/onboot$ export X="^usr\/local\/bin\/zvbi-atsc-c."
tc@E310:~/onboot$ export X="^usr\/local\/bin\/zvbi-atsc-c.$"

Please

[Rich]

Hi jazzbiker
I take it he's searching for a literal period at the end of the line.
I added a period to that entry in the provides file and repeated
the search:

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tc@E310:~/onboot$ export X="usr\/local\/bin\/zvbi-atsc-cc"
tc@E310:~/onboot$ time busybox grep "^$X.$" ../Scripting/LddCheck/provides-10.x-x86.db
usr/local/bin/zvbi-atsc-cc.
real    0m 0.49s
user    0m 0.38s
sys     0m 0.03s
tc@E310:~/onboot$ time busybox awk 'BEGIN {RS="\n"} /'"^$X\.$"'/{ print $0 }' ../Scripting/LddCheck/provides-10.x-x86.db
usr/local/bin/zvbi-atsc-cc.
real    0m 0.62s
user    0m 0.49s
sys     0m 0.09s
tc@E310:~/onboot$ time grep "^$X.$" ../Scripting/LddCheck/provides-10.x-x86.db
usr/local/bin/zvbi-atsc-cc.
real    0m 0.21s
user    0m 0.03s
sys     0m 0.03s
tc@E310:~/onboot$ time awk 'BEGIN {RS="\n"} /'"^$X\.$"'/{ print $0 }' ../Scripting/LddCheck/provides-10.x-x86.db
usr/local/bin/zvbi-atsc-cc.
real    0m 0.52s
user    0m 0.35s
sys     0m 0.08s
tc@E310:~/onboot$

[jazzbiker]

Hi Rich,

Thanks for this test, as we can see everything the same. Sorry, I was not attentive enough and missed that You've already added anchors while using the pattern.
 

I take it he's searching for a literal period at the end of the line.

Probably the period meant "any symbol", but anyway benchmark results are the same. thank You very much!

[Rich]

Hi jazzbiker
I see. I'm used to using a question mark to match a single character:

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tc@E310:~$ ls -l J?.jpg
-rw-r--r-- 1 tc staff 34836 Feb  2  2022 J1.jpg
-rw-r--r-- 1 tc staff 52988 Feb  2  2022 J2.jpg
-rw-r--r-- 1 tc staff 66236 Feb  2  2022 J3.jpg
tc@E310:~$
But grep seems to need a period:

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tc@E310:~$ ls -l | grep "J.\.jpg"
-rw-r--r--  1 tc staff   34836 Feb  2  2022 J1.jpg
-rw-r--r--  1 tc staff   52988 Feb  2  2022 J2.jpg
-rw-r--r--  1 tc staff   66236 Feb  2  2022 J3.jpg
tc@E310:~$

[jazzbiker]

Hi Rich,

Those "?" and "*" You mean are not regex but globbing symbols. As far as I understand the strings in the command line including such symbols are expanded by the shell interpreter according to the files existence (omg). If You'd be lucky to :-)

Here is the program to show its arguments:

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tc@box:/tmp/glob$ cat ggg.c
#include <stdio.h>
int main(int argc, char *argv[]) {
    while (--argc) printf("%s\n", argv[argc]);
    return 0;
}

Let compile it:

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$ tcc -o ggg ggg.cand add some spam:

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$ touch ggh ggk
Then:

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tc@box:/tmp/glob$ ./g*
./ggk
./ggh
./ggg.c

And:

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tc@box:/tmp/glob$ ./ggg ./g*
./ggk
./ggh
./ggg.c
./ggg

But:

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tc@box:/tmp/glob$ ./ggg "./g*"
./g*

:-)

As far as I know regexes are used by ed, grep, sed, find, vi (maybe some others?). Regexes may be basic, extended, perl-style, lua-style, and maybe some others.

Have a nice regex!

[Rich]

Hi jazzbiker

... Then:

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tc@box:/tmp/glob$ ./g*
./ggk
./ggh
./ggg.c
...

That's pretty slick. First  ggg  gets expanded invoking the program, then
the remaining 3 filenames get expanded and passed to the program.

[patrikg]

Just a thought with this, the shell globbing feature has some limits, like the command line max char length.

In my shell in my Arch, i can get the max value when executing this command.
This command is new to me..and when using option -a i get all values being set.
Learning every day something new.
Don't know if this also contain the env vars.

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getconf ARG_MAX
2097152
What i can see it's set to 2MB.

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echo $((1024*1024*2))
2097152

If i google a bit of this i also find that you can get this from xargs iike this.

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xargs --no-run-if-empty --show-limits </dev/null


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Size of command buffer we are actually using: 131072

Happy hacking on your keys.